Polymerisation kinetics and optical phenomena of photoactive dental resins

Globally, several shortcomings of dental resin based composites (RBCs) remain. This may be related to problems associated with incomplete conversion (40-70%), polymerisation shrinkage (1-4% by volume) and the stress generated at the tooth/restoration interface. Additionally, the increased number of technique sensitive incremental steps required to fill relatively large cavities is due to inefficient light transmission at depths greater than 2mm. The current investigation demonstrates the applicability of the exposure reciprocity law in photoactive dental materials in order to try and improve these shortcomings. The development techniques that will allow dynamic monitoring of optical and physical change will aid material development with the goal of improving cure depths. The current investigation has demonstrated the use of several analytical techniques (FT-IR spectroscopy, UV-Vis Spectroscopy and low coherence interferometry) and shown the complexity of optical phenomena within RBCs, which are affected by material composition as well as cavity dimensions. Whilst research continues to develop a novel RBC with reduced shrinkage and improved depths of cure, there is currently no commercially available solution to such problems. Consequently a better understanding of the setting reaction, optical properties and physical properties will aid material development